[Talk-GB] The curious case of USRN 20602512
Kai Michael Poppe - OSM
osm at poppe.dev
Fri Jul 10 15:00:33 UTC 2020
Thank you for this absolute masterpiece of detective work, Marc! I'd never thought that looking through old Notes would spark such an interest :)
As reported before, my own dip into having USRN data underlying JOSM at that particular point showed that this stub (in USRN the part where the barrier is to the northeast of the way isn't shown, so I guess that's really a small part of highway=footway) is recorded with the USRN you named. So I also believe that this isn't something to find copyright infringements - because the way exists, Google Street view clearly shows people walking along that way.
After not having any luck in finding out of copyright maps that helped I wondered, if a FOI request to Ealing Council, naming the exact location and asking for the name would be fruitful. Did anyone ever try something like this? Would this then be seen as a source compliant to the ODbL?
Am 10. Juli 2020 12:27:24 MESZ schrieb Mark Goodge <mark at good-stuff.co.uk>:
>Apologies for the long read, but this may be interesting to some folk.
>This follows on from my earlier response to Kai Michael Poppe about
>"Fairfield Road" in Ealing.
>On 04/07/2020 12:02, I wrote:
>> To find the USRN of the path, you need to use the lookup tables supplied
>> by OS. Doing that, we find that the associated USRN is 20602512.
>> Now, there's no open data source which will directly tell you the name
>> of a USRN (at least, not until we start putting them into OSM). The long
>> way of doing so is to find the matching LineString in OS OpenMap Local,
>> and see what name it has there.
>> However, it can be done directly via a non-open source. If you go to
>> https://www.findmystreet.co.uk/map and zoom in on the location, then
>> click the street to bring up the USRN details, it will give the name
>> (and also confirm that the USRN from the OS lookup table is correct). Or
>> use the search box and search for USRN 20602512.
>> From an OSM point of view, that would normally be a dead end. Even if
>> you can view the information on a non-open source, you can't incorporate
>> it into OSM. However, in this case, we already have an abbreviated name
>> from an open source. So all we are learning from the closed source is
>> the full text of the abbreviation. Whether that makes it acceptable to
>> include the full name into OSM is a matter of debate. I'll leave that
>> decision up to others, but, for reference, the name of the street is
>> Fairfield Road.
>I've been doing a bit more research in this, as it piqued my interest.
>And the results are a little surprising.
>For a start, USRN 20602512 doesn't match Fairfield Road in OS LocalMap
>Open. In fact, there's no Fairfield Road anywhere near there in OSLMO.
>Matching the coordinates indicates that, as far as OS is concerned, it's
>a part of Southdown Avenue. That's not particularly unusual, access
>roads off named streets often don't have a name of their own, they're
>either completely unnamed or share the name of their parent street.
>However, I did wonder whether this might just be a limitation on OS Open
>Data, and whether MasterMap might actually include the name. That's not
>reusable in OSM, of course, but it might help point to an open source
>that does contain it.
>But it seems that even MasterMap doesn't have that name. You can check
>that by looking at Ealing's online GIS website:
>This is a planning application map, but it's just a window into their
>GIS system and you can turn off the planning layers. Anyway, zoom all
>the way in to the street in question - I can't give you a persistent
>link, but it's just above the LA boundary in the bottom middle of the
>map - and... it still has no name. At the highest zoom level, this is
>MasterMap, and every named object has its name displayed. But there's no
>Google, also, knows nothing of a Fairfield Road here. Using the Maps API
>to query the coordinates of USRN 20602512, we either get Southdown
>Avenue, again, or Boston Gardens, which is the postal address of
>buildings facing Boston Road. You can see that name on the road sign via
>So, it seems that Fairfield Gardens isn't known to either OS or Google.
>It is shown (in abbreviated form) on streetmap.co.uk, but at that zoom
>level, in London, that's based on the Bartholomew A-Z maps rather than OS.
>Given that, we can't include the name "Fairfield Road" in OSM as it's
>only available from non-open sources. But even those non-open sources
>don't agree on the name. That seems to me to lead to two possibilities:
>1. It doesn't exist at all. It's just a map trap designed to catch out
>unwary copyright infringers. That's certainly a possibility, and A-Z
>maps are known to use those. But that doesn't explain its presence in
>the USRN database.
>2. The USRN name is wrong, but that error has propagated to the A-Z maps.
>Personally, I think that the second option is the most likely. And, if
>so, it wouldn't be the only error in USRN. One of the things I had to
>deal with a few years ago, in my capacity as a district councillor, was
>a country lane in my ward that had the wrong name assigned to it in
>USRN. After a bit of investigation, we concluded that it had simply been
>a transcription error back in the late 90s when the local gazetteer was
>first digitised, but it had gone unnoticed for a couple of decades
>simply because the wrong name never appeared anywhere in public until it
>eventually cropped up on a planning application. Getting the name
>corrected wasn't an easy task, because of the length of time it had been
>wrongly recorded, but we did eventually manage to get it sorted out and
>the correct, historic name of the lane assigned to the USRN.
>But that's not the only one. The USRNs for where I grew up, out in the
>middle of the countryside in West Suffolk, are listed as either "Poultry
>Road" or "Sedge Fen" in the USRN database. You can see that by looking
>at https://www.findmystreet.co.uk/map and searching for 14610160. But,
>in reality, the road name is "Sedgefen Road", and this is correctly
>shown by MasterMap, Google and OS LocalMap Open.
>This is, of course, one of the problems with proprietary data. It can be
>difficult to spot errors, because the people who are most likely to spot
>errors - members of the general public with local knowledge - tend not
>to have easy access to the data.
>So this is a bit of a warning, really, for the open mapping community.
>Although the open data release of USRN ids and coordinates is welcome,
>don't be tempted to look up street names on the street list published,
>with a restrictive licence, on https://www.findmystreet.co.uk and then
>copy them to our own data. Because it simply isn't reliable enough as a
>guide to actual usage, even if it is what the "official" name of the
>road may be. Stick to OS Open Data and local knowledge.
>Talk-GB mailing list
>Talk-GB at openstreetmap.org
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